1. Field of the Invention
This invention relates generally to warning systems for aircraft that alert the pilot of an aircraft of a hazardous flight condition in order to enable the pilot to take appropriate corrective action. More particularly, the present invention relates to a warning system that monitors various flight parameters of the aircraft, particularly during an approach to a landing, and advises the pilot when the airspeed of the aircraft (kinetic energy), and the energy being generated (thrust) is too low to maintain the desired flight path.
2. Description of the Prior Art
Various systems for warning the pilot of a hazardous flight condition are known. Such systems generally monitor various flight parameters of an aircraft and generate a warning if the descent rate or the closure rate of the aircraft is excessive, if there is insufficient terrain clearance, if the altitude loss after take-off is excessive and if the aircraft is below the glideslope. An example of such a system is disclosed in U.S. Pat. No. 3,946,358.
While the prior art warning systems provide warnings upon the occurrence of various hazardous flight conditions, it is also desirable to provide a warning of a low airspeed condition, particularly for automated aircraft where engine thrust is automatically controlled by a computer aboard the aircraft. Such a low airspeed warning system is particularly useful during an approach to a landing where the engines may be throttled back and the desired flight path maintained by adjusting the angle of attack of the aircraft. Under such conditions, the aircraft could lose airspeed without the pilot realizing it since the aircraft is under computer control until the airspeed is insufficient to permit the aircraft to fly.